For generating electricity from wind energy, many wind turbines can be arranged in a wind park and can feed their output into a utility grid. The wind turbines of a wind park can be controlled collectively or individually by a park pilot or other control means that issues appropriate commands or performance setpoints. Inside a wind turbine, a turbine controller receives these commands and uses them to control the relevant elements of the wind turbine. At intervals, a wind turbine may require local servicing, for example to perform a diagnostic sequence or a maintenance routine. To this end, it is necessary for an operator or service technician to “disconnect” the turbine controller from the park pilot so that it can be controlled locally. To this end, in a known approach, a local operator panel can be connected to the turbine controller, for example over an RS422 connection. The turbine controller can be placed in a local mode of operation by throwing a mechanical or electric switch from a “remote” position to a “local” position. The switch might physically interrupt or break the connection to the outside world to ensure that the wind turbine cannot be remotely controlled by the park pilot, or the turbine controller can logically ignore any control commands or setpoints originating from outside when the switch is in the “local” position. The RS422 connection between the local operator panel and the turbine controller is physically and logically separate from a main communication network between the park pilot and the turbine controller. Because the RS422 technology does not offer communication over long distances, the distinction between the local and remote modes of operation is clear in such a realisation.
In more modern networked wind parks, it is desirable to connect all elements that communicate with one another using network technology. During a maintenance procedure in a wind turbine, it is necessary to ensure that the operator has full control over that wind turbine in which he is located. However, in a fully networked system, it can be problematic to identify where an operator is located. In a networked wind park, this is a complicated issue, since control commands are effectively sent over a network. One outcome of this might be that a local control command intended for one wind turbine might be erroneously sent to another wind turbine located in the vicinity. For example, a control command broadcast as a data packet from an operator panel in one wind turbine might also erroneously be received by a control arrangement of another wind turbine, if that other control arrangement happens to have the same address as the control arrangement for which the packet was intended or an incorrect address was entered when sending the control command. Such duplicate addresses can only be avoided if great care is taken in the configuration, and errors cannot be ruled out completely.
Also, control commands issued by a park pilot or originating from a customer server might be picked up and carried out by the turbine controller of a wind turbine that should in fact be locally controlled by an operator. Such conflicts could result in damage to wind turbine components and might even present a safety risk for the operator.